INTERFACE MICROCRACK NUCLEATION

THE ZENER-STROH mechanism of microcrack nucleation by a dislocation pi le-up or band impinging upon an interface has been believed to be one of the basic mechanisms of microcrack nucleation in polycrystalline ma terials. In the case of different elastic properties of composite cons tituents, this problem is accurately solved in the present paper. The minimum number of elementary dislocations in the band necessary to for m a microcrack, as well as the interface microcrack length are found i n terms of physical properties and the number of elementary dislocatio ns in the band. A band bears a stronger singularity than a pile-up, an d therefore the obtained solution can serve as an upper bound estimate of the solution for the pile-up. The results of the paper may be used for the direct measurement of the true interface surface energy by an experimental observation of the nucleation of an interface microcrack .